CB1100 Idle speed instability problem

[beardyweirdy@me.com_imp]

A question for those who are experiencing the High / Low RPM Idling problem: Are you guys watching your fuel mileage closely? I have kept a strict record of my mileage since day 1 (13,000 miles now), and my mileage varies erratically. I chalked it up to not carefully refilling the tank exactly the same each time because my riding style rarely varies. But, when I replaced my battery my bike ran perfectly for the next 1 1/2 tanks of fuel, and I recorded one of the higher (47.4 mpg) fuel consumption readings (and this was with higher than average around town riding). I never thought about correlating my fuel mileage to the high/low RPM problem, but just "maybe" there is a connection? I've read where some members average 50+ mpg (MR. Ferret). I have averaged 45.7 mpg since I purchased this bike, and I ride it very conservatively, with about 97% freeway riding. I've exceeded 50 mpg on a few occasions, and I've dipped as low as 37 mpg, with no discernible difference in riding style. I don't know if the idle issue has any affect on my mileage, but seeing how the idle problem comes and goes, and my mileage varies, maybe there is some connection?

Hey Dave,
I have noticed a massive difference in fuel consumption. I have a Whitehouse tank and the last time I replaced it, I got the fuel gauge float stuck up in the high position, so the fuel gauge reads full all the time. So since then, which was about 6-8 months ago, I've been using my trip meter to keep an eye on how much fuel I've got left.

Using this method, I ran out of fuel one day with only 110-20 miles showing on the trip meter. Other times I'd been getting 160-170 miles between refills. Usually taking about 15L with another 3-4L left in the tank.

I put this down to exuberant riding and the fitting of the TSR Air Funnel Kit, which opens up the air intakes by 10mm. (Although you would think it'd run lean if anything). After putting it back together I was ragging it and just thought, Wow, this thing sucks juice when you thrash it.

I then got cautious and filled up again when the trip meter hit 110 and there was at least 1/3 of a tank left. Equating to about 170 miles a tank with a few Litres left in. Massive diff.

Since then I've kept an eye on it and filled up when I pass a gas station after 100 miles or so. I've had drastically different amounts of gas left in the tank.

The top and tail of all this waffle is yes, I have noticed a massive difference in fuel consumption. I wouldn't have noticed before I got the fuel gauge stuck as I just filled up when the gauge got low...

I've been experiencing the LOW idle problem since just after I bought the bike new 2 1/2 years ago. I've never seen the HIGH idle issue.

Just to say that I do ride the bike very differently at times. I have my girlfriend on the back sometimes and ride super smooth with steady acceleration. Other times, when I'm solo, I thrash the living daylights out of it and red line it regularly. That said I was still surprised at the difference in MPG, although maybe I shouldn't be.

[johnf514_imp]

simple suggestion

IF you guys are still under warranty, can't you simply demand your dealer to replace the throttle body under warranty?

You'd help us all by making the issue official to Honda.
If Honda can collect a larger number of faulty parts, maybe they can find a common root cause in those faulty parts?

Because, lets face it, everything that has been tried out here or suggested here, simply does not work.

My bike has been out of warranty for over a year now, and I have not given up trying to fix this myself yet. John's problem was corrected by replacing the IACV, so that's what I will probably do next. But, first I am going to write a letter to Honda and see how they reply. I already talked to my dealer and they were clueless.

Hi Dave, happy to help out with this in any way I can.

If you like, you can reference my case as Honda sent a tech to the dealership. This was with Central Florida Powersports in Kissimmee, FL, around Nov 8, 2016. The service tech at the dealership is Jimmy Le. Not sure of the Honda tech's name.

[dave]

simple suggestion

IF you guys are still under warranty, can't you simply demand your dealer to replace the throttle body under warranty?

You'd help us all by making the issue official to Honda.
If Honda can collect a larger number of faulty parts, maybe they can find a common root cause in those faulty parts?

Because, lets face it, everything that has been tried out here or suggested here, simply does not work.

My bike has been out of warranty for over a year now, and I have not given up trying to fix this myself yet. John's problem was corrected by replacing the IACV, so that's what I will probably do next. But, first I am going to write a letter to Honda and see how they reply. I already talked to my dealer and they were clueless.

Hi Dave, happy to help out with this in any way I can.

If you like, you can reference my case as Honda sent a tech to the dealership. This was with Central Florida Powersports in Kissimmee, FL, around Nov 8, 2016. The service tech at the dealership is Jimmy Le. Not sure of the Honda tech's name.

Hi Dave, happy to help out with this in any way I can.

If you like, you can reference my case as Honda sent a tech to the dealership. This was with Central Florida Powersports in Kissimmee, FL, around Nov 8, 2016. The service tech at the dealership is Jimmy Le. Not sure of the Honda tech's name. Thank you John.

[dave]

I just did some research and discovered the Idle Air Control Valve (motor assy) Honda part number 16430-MFJ-D01, is used by over 100 different Honda models, dating back to 2007! As soon as I get time (need to schedule an all-day Saturday) I will replace mine. I just don't trust a shop mechanic to work on my bike. If this doesn't work then I have no choice but to rely on Honda to come up with a fix.

[Magnus_imp]

Let me know how it goes. I too am having the 1500rpm idle problem. The Idle Air Control Value does not look easy to get to. Do you have to remove the motor?

[Lord Popgun]

You do not have to remove the engine to get to the IACV.

[dave]

Let me know how it goes. I too am having the 1500rpm idle problem. The Idle Air Control Value does not look easy to get to. Do you have to remove the motor?

I will keep this post updated. This is a weekend job for me, and I have other plans for the next three weekends so I won't get to is as soon as I would like. Replacing the IACV cured Beardy's idle issue, so I figure I will try it (I just do not trust taking my bike to the shop).

[Lord Popgun]

Check this post out: http://cb1100forum.com/forum/showthread....#pid163671

The dealer found the IACV connector "bent" and corroded.

Its always good practice to inspect connectors when working on things like this. And who knows maybe its your problem.

[dave]

Check this post out: http://cb1100forum.com/forum/showthread....#pid163671

The dealer found the IACV connector "bent" and corroded.

Its always good practice to inspect connectors when working on things like this. And who knows maybe its your problem.

Thanks Popgun, I will inspect for this. I meant Johnf514, not Beardy, in my above post.

[beardyweirdy@me.com_imp]

Hey All,

Just thought I'd let you know how I was going on with the on going Idle Prob.

I managed to get the bike back to the dealers yesterday and they successfully re-flashed the ECU with the latest Map from Honda. I'm not sure why it worked this time but I had called Honda UK to question what was going on and they offered the dealer some tech support and pos. a new disk/Software.

The dealer gave me a 'Honda ECM Update Report'. It states the previous ECUID which is 01019D0102
and an After the Update ECUID of 01019D0103. I don't know if this is specific to my bike or a general code for the re-flash.
There is also a note at the end of the report giving the code: 38770-MGC-D53_-M1.rwf.
I have no idea what that code refers to but it's the only other info on the report that isn't obvious stuff like date, VIN, milage etc....

After the re-flash I gave it a celebratory thrashing followed by a 30 min trawl thru London rush hour traffic, trying my best to emulate the riding style that had usually preceded the fault. It has mainly occurred when two up in town and dawdling. I was on my own yesterday but I road as tho I was carrying a pillion. I dragged the back brake to put the motor under load and slipped the clutch. I also sat in traffic and didn't cut thru and lane split so much as I would do with someone on the back.

I couldn't get it to show the fault. I let the revs fall to tick over and they stayed solid at 1050. Now I don't know if it will stay like that. We'll have to see what happens over the next week or so. I have a week or so at home so I'll be taking my girlfriend into work most days next week. That will give us a good test. But I'll keep my eye on it and report back.

On a side note, It has reset all the good things that Guhl Motors did to my ECU. I'm going to the USA on a work trip in a couple of weeks, so I'll take my ECU with me and get it re-done while I'm there.

I have spoken to Don at Guhl perviously and he's expecting the ECU. He said he'd go through it, work out what Honda had modified and then re-write their map to incorporate the Honda modifications.

I guess that way there is an option for you guys in the states to get the new map, via Guhl, if Honda USA isn't offering it to their customers.... if it works that is ;-)

It is interesting that the IACV replacement/overhaul seems to be working for some. I was going to test mine, as per the manual and see how it faired. Dave, did you run thru the diagnostic test in the manual? if so what did you find?

I'm not going to change anything else for a while tho, so I can really see if the new map is working for me .... Only change one thing at a time when testing and all that.